A sensor node of a wireless sensor network may need to run on a given number of batteries for a long period of time, e.g., several years on a pair of batteries. In one example, changing the batteries or recharging the batteries in each sensor node of the wireless sensor network may be infeasible or unpractical because the sensor nodes may be physically inaccessible or deployed in an area that is difficult to access. In another example, the scale of deployment may be very large, thereby making the operation of changing or recharging the batteries costly and labor intensive. Thus, increasing the lifetime of the batteries presents a difficult challenge for a service provider of such wireless sensor networks.